1. Technical Field
The present invention relates to a magnetic recording device, and in particular, relates to a magnetic recording device used as a computer external storage device, or the like.
2. Related Art
In a magnetic disk device such as a hard disk, a recording and reproduction of information is carried out in a data region on a magnetic disk in a condition in which a magnetic head flies above the magnetic disk. In recent years, in order to further improve recording density, there has also been proposed a magnetic head wherein it is possible to reduce the flying height of the magnetic head by incorporating a heat element such as a heater in the magnetic head, and causing the flying surface of the magnetic head to thermally expand to the magnetic disk side (JP-A-2006-190454). By employing this kind of technology, the reduction of the flying height of a magnetic head slider (the distance between the bottom surface of the magnetic head slider and the magnetic disk surface) in order to increase recording density in a magnetic disk device has advanced rapidly to a current level of 1 to 2 nm.
However, due to this kind of reduction of the magnetic head slider flying height, intermittent contact between the magnetic head slider and the magnetic disk while the magnetic recording device is being started up is unavoidable. Furthermore, a contact magnetic recording method that promotes the reduction of the magnetic head slider flying height, and assumes a continuous contact between the magnetic head slider and magnetic disk, has also been proposed, and from now on, an optimum design of a magnetic recording disk surface that assumes an intermittent or continuous contact is also required.
Under this kind of condition, the magnetic head flying position or contact position is liable to be affected by external factors, such as coarseness or undulation of the magnetic disk surface. In particular, the magnetic head slider has a natural frequency caused by a suspension that holds the magnetic head slider, and a natural frequency caused by an air film between the magnetic disk supporting the flying of the magnetic head and the magnetic head slider (hereafter called the “magnetic head air film”), and when a phenomenon of exciting of the natural frequencies occurs due to the external factors, the magnetic head slider resonates, and there is a danger that a stable write/read operation will no longer be possible (JP-A-2005-116112).
Also, a lubrication layer is formed on a current magnetic disk surface by applying a lubricant, such as Z-tetraol, with a polar end group that has a strong adsorption to a protection layer of the magnetic disk. However, in order to further promote the adsorption characteristic, it has become common to carry out a process such as an ultraviolet beam irradiation on the magnetic disk surface, thus hydrophilizing the surface of the protection layer. As a result of this, the lubricant in the lubrication layer has a stronger adsorption to the protection layer, and there is a tendency for the lubrication layer surface distribution to be controlled by surface form factors, such as coarseness and undulation of the magnetic disk surface. Consequently, even though the lubrication layer exists, the problem of magnetic head slider resonance still persists.
However, to date, the only way of suppressing the oscillation of the natural frequencies of the flying head slider with magnetic disk side conditions has been by planarizing forms such as coarseness and undulation of the disk surface as far as possible.